Thermal waters have been recognized as a source of health and energy since ancient times, and today there is still interest in balneotherapy as a method of treating various diseases, rehabilitation and prevention. In Poland, as many as 12 spa towns use healing thermal waters in their activities. They include: Busko-Zdrój, Ciechocinek, Jelenia Góra-Cieplice, Gołdap, Inowrocław, Iwonicz-Zdrój, Konstancin-Jeziorna, Lądek-Zdrój, Rabka-Zdrój, Uniejów, Ustka and Ustroń. Healing thermal waters are not only used there for medical treatments, because they also supply the brine graduation towers, are the base for the production of cosmetics and are also used in drinking treatments. Uniejów spa is a part of the cascade system, so the healing waters of higher temperature are also used for heating apartments. Depending on the mineral composition of the waters, they can be used in the treatment of, among others: diseases of the musculoskeletal system, rheumatology, osteoporosis, skin diseases, diseases of the upper and lower respiratory tract, cardiological diseases, diseases of the digestive system, hypertension, obesity, diabetes. All treatments are non-invasive, because the vast majority of them are carried out in the form of bathing, irrigation, inhalation or drinking treatments. The paper also shows the most promising towns in terms of the development of balneotherapy, including Stargard, Pyrzyce, Toruń, Konin and Grudziądz. Balneotherapy in Poland is currently at a difficult time, which is related to the inability to function of many facilities due to the COVID-19 pandemic. However, there is a possibility that when the pandemic and its effects are eliminated, balneotherapy and spa treatment will experience a renaissance.

The aim of the presented work was an attempt to verify the geothermal conditions in the Polish Lowlands (Lower Jurassic and Lower Cretaceous reservoir) based on new geological information. The paper presents geothermal conditions in the Polish Lowlands according to the state of recognition at the end of 2022 in order to update the hydrogeothermal conditions in selected regions. Based on the scientific and research works published so far as well as numerous geothermal investments, and geological information from twenty-three new exploratory drilling events performed in the years 2000–2022 (nineteen of which were performed/documented after 2006), the authors undertook to update forecasts of the top surface of Lower Jurassic and Lower Cretaceous formations, the total thickness of these formations and the potential discharge of wells. The analysis was performed using the QGIS Desktop 3.24.1 software, a cross-platform and free open-source geoinformation software application (GIS ) that enables the viewing, editing and analyzing of spatial data and the creation of maps. The correction covered the course of the isolines on all six analyzed maps. The presented analysis made it possible to make a spot correction of the forecasted course of the isoline in relation to the maps published earlier in the Atlas of geothermal resources in the Polish Lowlands. Mesozoic formations developed in 2006, edited by Wojciech Górecki. Information obtained from newly drilled geothermal boreholes enabled the local correction of the forecasted values of individual parameters while maintaining the general trend.